JP2007266993A - Data transmission method and switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a mobile station apparatus to receive data relevant to communication properly even in an environment where handover is performed frequently. <P>SOLUTION: Mobile station apparatus information showing a mobile station apparatus 10 is acquired on a base station device 20 side. Data are transmitted from a PDSN 30 to the mobile station apparatus 10 based on the acquired mobile station apparatus information. When the mobile station apparatus 10 corresponding to the mobile station apparatus information performs handover from a base station device 20-1 to a base station device 20-2, the mobile station apparatus information is held for a prescribed time by the base station device 20-1. Streaming data are transmitted from the PDSN 30 to the base station device 20-1 based on the mobile station apparatus information until a prescribed time passes. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a data transmission method and an exchange.

  In the mobile communication system, handover is performed. The details of this handover technique vary depending on the type of mobile communication system, but are performed as follows, for example.

  First, during communication with the base station apparatus A, the mobile station apparatus C periodically receives a notification signal from a neighboring base station apparatus, acquires the reception level, and reports it to the base station apparatus A. When there is a base station apparatus whose reception level is higher than the signal transmitted by the base station apparatus A, the base station apparatus A checks the channel availability of the base station apparatus (here, the base station apparatus B). If there is a vacancy, the mobile station apparatus C transmits a handover request indicating that the mobile station apparatus C should be handed over to the base station apparatus B, and instructs the mobile station apparatus C to perform handover.

The exchange that has received the handover request transfers the handover request to the base station apparatus B, and performs processing for establishing a communication path for the mobile station apparatus C with the base station apparatus B. In addition, the mobile station apparatus C instructed to perform handover performs a process for establishing a communication path in a wireless section with the base station apparatus B. When these processes are completed, communication can be performed between the mobile station apparatus C and the exchange, and the exchange changes the transmission destination of data to be transmitted to the mobile station apparatus C to the base station apparatus B. In this way, handover is realized.
JP 2005-31646 A

  However, in the above handover, there is a certain amount of time from when the wireless channel communication path is established between the mobile station device C and the base station device B until the exchange changes the data transmission destination to the base station device B. It takes. For this reason, in communications in which retransmission control at the time of data transmission / reception is restricted, such as broadcasting to a plurality of terminals including the mobile station apparatus C and multipoint video conferences, the mobile station apparatus C appropriately transmits data related to communication. There are cases where it cannot be received. That is, since the mobile station apparatus C cannot receive data for the certain period of time, there may be a case where the mobile station apparatus C cannot receive data properly during handover.

  When the mobile station apparatus C is located near the boundary of the communication cell between the base station apparatus A and the base station apparatus B, frequent handovers are performed between the base station apparatus A and the base station apparatus B. Will be. In such a case, the time during which the mobile station apparatus C cannot receive data further increases.

  Accordingly, one of the objects of the present invention is a data transmission method and a data transmission method capable of enabling a mobile station apparatus to appropriately receive data related to communication even in an environment where handovers are frequently executed, and To provide an exchange.

  A data transmission method according to the present invention for solving the above-mentioned problem is a mobile communication system including a base station device and an exchange connected to the base station device, from the exchange via the base station device. A data transmission method for transmitting data to a mobile station device, on the base station device side, acquiring mobile station device information indicating the mobile station device, and based on the acquired mobile station device information, A data transmission step of transmitting the data from the exchange to the mobile station device via the base station device, wherein the mobile station device corresponding to the mobile station device information is transferred from the base station device to another base station. When handing over to a device, the base station device side holds the acquired mobile station device information for a predetermined time, and keeps the held movement until the predetermined time elapses. Device to send the data via the base station apparatus from the exchange on the basis of the information, characterized in that.

  According to this, when the mobile station apparatus is handed over from the first base station apparatus to the second base station apparatus and further handed over from the second base station apparatus to the first base station apparatus within a predetermined time. Even if it exists, the mobile station apparatus can receive the data concerning communication appropriately.

  In the data transmission method, the mobile station device corresponding to the mobile station device information is transferred from the other base station device to the base station while the mobile station device information is held on the base station device side. When handed over to the apparatus, the data transmission from the exchange through the base station apparatus may be continued.

  According to this, transmission of data related to communication from the exchange can be reliably continued.

  In each of the data transmission methods, the data may be streaming data.

  According to this, when a handover is performed on streaming data such as video data transmitted in television broadcasting or multi-point video conference, among the data, the mobile station device to be handed over appropriately determines the data related to communication. Can be received.

  The mobile communication system according to the present invention is an exchange that is connected to a base station apparatus and transmits data to the mobile station apparatus via the base station apparatus, and includes mobile station apparatus information indicating the mobile station apparatus. An acquisition means for acquiring, a data transmission means for transmitting the data to the mobile station apparatus via the base station apparatus based on the acquired mobile station apparatus information, and a mobile station apparatus corresponding to the mobile station apparatus information However, in the case of handover from the base station apparatus to another base station apparatus, a time measuring means for measuring a predetermined time is provided, and the time until the predetermined time elapses in the time measurement by the time measuring means is acquired. The data is transmitted to the base station apparatus based on mobile station apparatus information.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a system configuration of a mobile communication system 1 according to the present embodiment. As shown in the figure, the mobile communication system 1 includes a plurality of mobile station apparatuses 10, a plurality of base station apparatuses 20, a PDSN (Packet Data Service Node, packet switch) 30, and a network 40.

  In the present embodiment, each mobile station device 10 performs IP communication with the network 40. Further, the network 40 multicasts streaming data to each mobile station device 10. The outline of each device for realizing these will be described below.

  First, the network 40 is a communication network including a computer that communicates with the mobile station apparatus 10 via the PDSN 30 and the base station apparatus 20. Here, the network 40 is a TCP / IP network. The network 40 transmits streaming data whose destination is a multicast group to the PDSN 30.

  The PDSN 30 is a computer that functions as a communication relay device. The PDSN 30 stores the above-described multicast table (a table that associates a multicast group including a set of one or a plurality of receiving terminals that should receive the same data and identification information of the mobile station device 10). The mobile station apparatus 10 that receives the streaming data transmitted from the network 40 is specified based on the above. Then, the destination of the streaming data is changed to the specified mobile station device 10, and the streaming data is transmitted to the base station device 20 in which the specified mobile station device 10 is located.

  The base station device 20 is also a computer that functions as a communication relay device. The base station apparatus 20 transmits the streaming data received from the PDSN 30 to the mobile station apparatus 10 that is the destination of the streaming data. The base station device 20 is identified for each mobile station device 10 from the channel (frequency (frequency division multiplexing), time slot (time division multiplexing), PN code (code division multiplexing), adaptive array antenna directivity (space division multiplexing), etc. Communication resources), and the streaming data is transmitted on the reserved channel.

  The mobile station apparatus 10 is a computer having a communication function, receives streaming data transmitted from the base station apparatus 20, and performs processing according to the streaming data.

  Base station apparatus 20 is fixedly installed in various places such as in the city, and transmits a notification signal with a predetermined transmission power. The mobile station device 10 periodically receives the notification signal transmitted by each base station device 20 during communication with the base station device 20. And it hands over to the other base station apparatus 20 according to the reception condition of an alerting | reporting signal.

  The PDSN 30 transmits at least a part of the multicast table to the base station apparatus 20 connected to the PDSN 30. The base station apparatus 20 receives and stores the multicast table transmitted from the PDSN 30. When a certain mobile station device 10 performs a handover from the first base station device 20 to the second base station device 20, the second base station device 20 uses the stored multicast table to It is determined whether or not streaming data to be transmitted to a mobile station apparatus 10 to be handed over (hereinafter referred to as a handover mobile station apparatus 10) is being transmitted to another mobile station apparatus 10. When it is determined that the transmission is in progress, the streaming data transmitted from the PDSN 30 to the handover mobile station apparatus 10 as the destination is received (the streaming data transmitted from the PDSN 30 by the handover mobile station apparatus 10 is received). The streaming data transmitted to the other mobile station apparatus 10 is also transmitted to the handover mobile station apparatus 10 until it is received).

  Further, when the handover mobile station apparatus 10 performs handover from the first base station apparatus 20 to the second base station apparatus 20, the PDSN 30 measures a predetermined time, and when the predetermined time has elapsed as a result of the time measurement In addition, it requests the first base station apparatus 20 to delete at least the identification information of the handover mobile station apparatus 10 from the multicast table stored in the first base station apparatus 20. Then, when there is a request for deletion from the PDSN 30, the first base station apparatus 20 executes deletion corresponding to the request with respect to the multicast table stored in the own station, and the request for deletion is received. Until then, at least the identification information of the handover mobile station apparatus 10 is held in the multicast table.

  More specifically, the process until the PDSN 30 counts the predetermined time is as follows. That is, first, during the communication with the first base station apparatus 20, the handover mobile station apparatus 10 periodically receives a notification signal from the neighboring base station apparatus 20 and acquires the reception level. If there is a base station apparatus 20 having a higher reception level than the signal being transmitted, the channel availability status of the base station apparatus (here, the second base station apparatus 20) is investigated, The station apparatus 10 transmits a handover request indicating that handover to the second base station apparatus 20 should be performed to the PDSN 30 and instructs the handover mobile station apparatus 10 to perform handover. Next, when the first base station apparatus 20 transmits a handover request indicating that the handover to the second base station apparatus 20 is to be handed over to the PDSN 30, and the PDSN 30 receives the handover request, the PDSN 30 Starts measuring the predetermined time. The predetermined time means, for example, a time from several tens of seconds to several minutes. Specifically, normally, in a mobile communication system, when the wireless connection between the mobile station device 10 and the base station device 20 is disconnected due to an abnormality in the wireless environment, the PDSN 30 is connected to the base station device 20. A fixed time is provided until the transmission of data to the terminal is completed (until the blocking process), but a predetermined time is set to be equal to the fixed time.

  Hereinafter, the configuration and functions of the mobile communication system 1 will be described in detail with reference to FIG.

  FIG. 2 is a diagram showing functional blocks of the mobile communication system 1. As shown in the figure, the mobile station apparatus 10 is functionally configured to include a reception unit 11, a reception level acquisition unit 12, a transmission unit 13, and a handover execution unit 14. The base station device 20 functionally includes a receiving unit 21, a transmitting unit 22, a receiving unit 23, a transmitting unit 24, a multicast table storage unit 25, an identical data transmission determining unit 26, a handover executing unit 27, a multicast table transmission requesting unit 28, The transmission unit 22 further acquires a duplication unit 221, the multicast table storage unit 25 further acquires a multicast table storage control unit 251 (not shown), and the multicast table transmission request unit 28 further acquires mobile station apparatus identification information. A part 281 is included. The PDSN 30 functionally includes a reception unit 31, a destination determination unit 32, a transmission unit 33, a reception unit 34, a transmission unit 35, a multicast table storage unit 36, a multicast table transmission unit 37, a handover execution unit 38, a predetermined time counting unit 39, and A deletion request unit 41 is included.

  First, data transmission / reception processing between the devices will be described.

  In uplink communication, the transmission unit 13 transmits data input from a communication processing unit (not shown) of the mobile station device 10 to the base station device 20. The receiving unit 23 receives the data transmitted in this way, and outputs the data addressed to the PDSN 30 or the network 40 to the transmitting unit 24. In addition, the base station apparatus 20 generates data to be transmitted to the PDSN 30 in each unit described later, and outputs the data to the transmission unit 24. The transmission unit 24 transmits the input data to the PDSN 30.

  The receiving unit 34 receives data transmitted from the base station apparatus 20, and outputs data addressed to the network 40 to the transmitting unit 35. The transmission unit 35 transmits the input data to the network 40.

  Next, in downlink communication, the receiving unit 31 receives data input from the network 40. Here, a part of this data is streaming data, and the destination is specified by the multicast group. The destination determination unit 32 acquires the multicast group (destination information) that is the destination of the streaming data received by the reception unit 31, and determines the mobile station device 10 that is the destination based on the multicast table.

  FIG. 3 is a diagram illustrating an example of a multicast table. As shown in the figure, the multicast table stores multicast group information indicating a multicast group, an IP address, and mobile station apparatus identification information for identifying the mobile station apparatus in association with each other.

  The network 40 assigns an IP address to each mobile station device 10. The destination of data transmitted from the network 40 to the mobile station apparatus 10 by transmission other than multicast transmission is specified by this IP address. However, in multicast transmission, the network 40 should transmit one or a plurality of streaming data to be transmitted. A representative IP address representing these is given to the mobile station apparatus 10, and the destination of streaming data is specified by this representative IP address. One or a plurality of mobile station apparatuses 10 to which the same representative IP address is assigned constitutes a multicast group, and the representative IP address becomes multicast group information.

  The network 40 associates the IP address of each mobile station apparatus 10 with the multicast group information to which each mobile station apparatus 10 belongs, and further identifies each mobile station apparatus 10 used in the mobile communication system 1 By associating identification information (hereinafter referred to as mobile station apparatus identification information), mobile station apparatus group information indicating one or more mobile station apparatuses 10 belonging to the group is generated for each mobile station apparatus group. The network 40 configures the multicast table based on the mobile station apparatus group information. The network 40 transmits at least a part of the multicast table thus configured to the PDSN 30. The receiving unit 31 receives at least a part of the multicast table transmitted by the network 40 and stores it in the multicast table storage unit 36.

  The destination determination unit 32 determines the mobile station device 10 that is the destination of the streaming data based on the multicast table stored in this way. Specifically, the destination determination unit 32 acquires a multicast group that is a destination of streaming data, and further stores one or a plurality of mobile stations stored in a multicast table in association with multicast group information indicating the acquired multicast group Acquire device identification information. Then, the mobile station apparatus 10 indicated by each acquired mobile station apparatus identification information is determined as a destination of streaming data.

  Here, the base station apparatus 20 stores a mobile station apparatus-base station apparatus correspondence table. FIG. 4 is a diagram illustrating an example of the mobile station apparatus-base station apparatus correspondence table. As shown in FIG. 4, the mobile station apparatus-base station apparatus correspondence table shows mobile station apparatus identification information and the base station apparatus 20 in which the mobile station apparatus 10 identified by the mobile station apparatus identification information is located. It is a table which memorize | stores and matches base station apparatus identification information.

  The destination determination unit 32 acquires the base station device 20 corresponding to the mobile station device 10 determined as the destination of the streaming data based on the mobile station device-base station device correspondence table, and for the acquired base station device 20 The transmission unit 33 is instructed to transmit the streaming data. When a plurality of mobile station apparatuses 10 are destinations for certain streaming data, the transmission unit 33 copies the streaming data correspondingly and transmits it to the instructed base station apparatus 20.

  The receiving unit 21 receives the streaming data transmitted by the PDSN 30 and outputs it to the transmitting unit 22. The transmission unit 22 wirelessly transmits the streaming data to the mobile station apparatus 10 that is the destination of the input streaming data. At this time, the transmission unit 22 may wirelessly transmit the streaming data to other than the mobile station device 10 that is the destination of the streaming data in accordance with the instruction of the same data transmission determination unit 26. This process will be described later. To do.

  The receiving unit 11 receives streaming data transmitted from the base station device 20 and outputs the streaming data to a communication processing unit (not shown) of the mobile station device 10, and the communication processing unit performs processing (for example, a display) according to the streaming data. Process to be displayed).

  Next, the handover process will be described.

  The transmission unit 22 provided in each base station device 20 periodically transmits a notification signal. This transmission is performed with a predetermined transmission power. The receiving unit 11 periodically receives this notification signal, the reception level acquisition unit 12 acquires the reception level (RSSI, Receive Signal Strength Indication) of the received notification signal, and each base station device 20 transmits it. The reception level of the broadcast signal is output to the transmitter 13. The transmission unit 13 transmits the reception level input from the reception level acquisition unit 12 to the base station apparatus 20.

  The reception unit 23 receives the reception level from each mobile station device 10 in communication with the base station device 20 and outputs the reception level to the handover execution unit 27. The handover execution unit 27 determines whether or not each mobile station device 10 should be handed over based on the reception level input from the reception unit 23. Specifically, for example, for the mobile station device 10-1, a base station device 20 (base station device 20-2) that transmits a notification signal having a higher reception level than the notification signal transmitted by the base station device 20 concerned. )), The channel availability status of the base station device 20-2 is investigated. More specifically, the base station apparatus 20-2 is inquired about the channel availability via the PDSN 30, and the result is acquired. Based on this result, the handover execution unit 27 determines whether or not the base station device 20-2 can accept the handover of the mobile station device 10-1 and start communication with the mobile station device 10-1. . Specifically, if there is a free channel, it is determined that communication with mobile station apparatus 10-1 can be started.

  When the handover execution unit 27 determines that the base station device 20-2 can start communication with the mobile station device 10-1, the handover execution unit 27 hands over the mobile station device 10-1 to the base station device 20-2. And instructing the PDSN 30 to hand over the mobile station device 10-1 to the base station device 20-2. Specifically, a handover instruction for instructing handover to the base station apparatus 20-2 is generated and transmitted from the transmission unit 22. In addition, a handover request for requesting the mobile station apparatus 10-1 to be handed over to the base station apparatus 20-2 is generated and transmitted from the transmission unit 24.

  The reception unit 11 that has received the handover instruction outputs this to the handover execution unit 14. When the handover execution unit 14 receives the input of the handover instruction, the handover execution unit 14 requests the base station apparatus 20-2 to allocate a channel. When this assignment is completed, a communication path is established between the base station device 20-2 and the mobile station device 10-1, and communication is started.

  The reception unit 34 that has received the handover request outputs this to the handover execution unit 38. When receiving the handover request, the handover execution unit 38 transfers this to the base station apparatus 20-2. The base station apparatus 20-2 receives the handover request transferred in this way at the receiving unit 21. In response to this handover request, a communication path for the mobile station device 10-1 is established with the PDSN 30. When this communication path is established, the PDSN 30 transmits a transmission destination of data to be transmitted to the mobile station apparatus 10-1 to the base station apparatus 20-2. Specifically, the mobile station apparatus-base station apparatus correspondence table is rewritten.

  The receiving unit 34 that has received the handover request also outputs this to the predetermined time counting unit 39. Then, the predetermined time counting unit 39 starts measuring the predetermined time based on the handover request from the receiving unit 34. Then, when the predetermined time has elapsed as a result of the time measurement by the predetermined time counting unit 39, the PDSN 30 sends the handover source base station apparatus 20-1 to the multicast table. In the multicast table stored in the storage unit 25, a deletion request is transmitted from the deletion request unit 41 via the transmission unit 33 so as to delete at least the identification information of the mobile station device 10-1. Then, the handover source base station apparatus 20-1 outputs the delete request received by the receiving unit 21 to the multicast table storage control unit 251. Based on the deletion request, the multicast table storage control unit 251 controls the multicast table storage unit 25 to delete at least the identification information of the mobile station apparatus 10-1 stored in the multicast table storage unit 25. To do.

 As described above, when the identification information of the mobile station apparatus 10-1 is deleted from the multicast table in the handover source base station apparatus 20-1, the PDSN 30 moves from the base station apparatus 20-1 to the mobile station apparatus 10-1. Data cannot be transmitted. The handover source base station apparatus 20-1 holds at least the identification information of the mobile station apparatus 10-1 in the multicast table until the deletion request is received.

  Of the data transmitted by the PDSN 30, data destined for the mobile station device 10-1 until the mobile station device-base station device correspondence table is rewritten and a predetermined time elapses in the time counting by the predetermined time counting unit 39. Is transmitted to the base station apparatus 20-1 and the base station apparatus 20-2. The establishment of the communication path between the base station apparatus 20-2 and the PDSN 30 is performed after the communication path is established between the base station apparatus 20-2 and the mobile station apparatus 10-1.

  In this way, the handover process of the mobile station apparatus 10 is performed. In this handover, as described above, the base station apparatus 20 transmits the streaming data to be transmitted to the handover mobile station apparatus 10 to be handed over to the base station apparatus 20 to other mobile station apparatuses 10 as well. If it is being transmitted, the streaming data transmitted to the other mobile station device 10 is also transmitted to the handover mobile station device 10. Hereinafter, the process for this will be described.

  First, the mobile station apparatus identification information acquisition unit 281 periodically acquires mobile station apparatus identification information of the mobile station apparatus 10 in communication with the base station apparatus 20. The multicast table transmission request unit 28 generates a multicast table transmission request including the mobile station device identification information acquired by the mobile station device identification information acquisition unit 281 and outputs the multicast table transmission request to the transmission unit 24. The transmission unit 24 transmits the input multicast table transmission request to the PDSN 30.

  The receiving unit 34 receives the multicast table transmission request transmitted from the base station apparatus 20 and outputs the multicast table transmission request to the multicast table transmitting unit 37. The multicast table transmission unit 37 moves from the multicast table stored in the multicast table storage unit 36 regarding one or more multicast groups to which the mobile station device 10 identified by the mobile station device identification information included in the multicast table transmission request belongs. The station device group information is read and output to the transmitter 33. The transmission unit 33 outputs the input mobile station device group information to the base station device 20 that has transmitted the multicast table transmission request. As a result, the transmission unit 33 transmits at least a part of the plurality of base station apparatuses 20, that is, a part of the multicast table related to the multicast group to the base station apparatus 20 communicating with the mobile station apparatus 10 belonging to each multicast group. That is, mobile station apparatus group information relating to the multicast group is transmitted.

  The receiving unit 21 receives the mobile station apparatus group information thus transmitted and outputs it to the multicast table storage unit 25. The multicast table storage unit 25 configures and stores a multicast table based on the input mobile station device group information. And when the mobile station apparatus 10 in communication with the own station is handed over to another base station apparatus 20, at least the identification information of the mobile station apparatus 10 is held until the deletion request is received from the PDSN 30 Like that.

  When the handover execution unit 27 receives a handover request from the PDSN 30 or receives a channel assignment request from the mobile station apparatus 10 in the handover process, the handover execution unit 27 outputs a message to that effect to the same data transmission determination unit 26.

  The same data transmission determination unit 26 is transmitting the streaming data from the base station device 20 when the mobile station device 10 (handover mobile station device 10) receiving the streaming data hands over to the base station device 20. The other mobile station device 10 is searched based on the multicast table stored in the multicast table storage unit 25. That is, the same data transmission determining unit 26 searches for another mobile station device 10 belonging to the same multicast group as the handover mobile station device 10 in the multicast table.

  When another mobile station device 10 is searched, the same data transmission determination unit 26 duplicates the streaming data transmitted to the other mobile station device 10 to the duplication unit 221, and the handover mobile station device 10 is also instructed to be transmitted.

  In accordance with an instruction from the same data transmission determination unit 26, the transmission unit 22 duplicates the streaming data being transmitted to the other mobile station device 10 in the duplication unit 221 and transmits it to the handover mobile station device 10.

  In this way, the base station apparatus 20 is also transmitting streaming data to be transmitted to the handover mobile station apparatus 10 to be handed over to the base station apparatus 20 to other mobile station apparatuses 10. In this case, the streaming data transmitted to the other mobile station device 10 is also transmitted to the handover mobile station device 10.

  This duplicate transmission process is performed until streaming data transmitted from the PDSN 30 with the handover mobile station apparatus 10 as a destination is received. Thus, in the mobile communication system 1, the real time property of the streaming data is ensured when the handover is performed.

  The PDSN 30 can immediately transmit streaming data to the handover mobile station apparatus 10 when the handover mobile station apparatus 10 is handed over again to the handover source base station apparatus 20 during a predetermined time. .

  In addition, when the handover mobile station apparatus 10 is handed over again to the handover source base station apparatus 20 before the predetermined time elapses, the PDSN 30 ends the measurement of the predetermined time by the predetermined time counting unit 39, Is cleared. As a result, it is possible to continue transmission of streaming data to the handover source base station apparatus 20, whereby the handover mobile station apparatus 10 reconnected to the handover source base station apparatus 20 Real-time performance is ensured.

  Hereinafter, each process described above will be described again in more detail with reference to a process sequence diagram.

  First, FIG. 5 is a sequence diagram illustrating a process in which the base station device 20-1 acquires a multicast table from the PDSN 30 and a process in which streaming data is transmitted in the mobile communication system 1. FIG. 6 is a sequence diagram showing a process for measuring a predetermined time in the PDSN 30 and a process based on the time measurement.

  As shown in FIG. 5, when communication paths are established between the mobile station device 10-1 and the base station device 20-1, and between the base station device 20-1 and the PDSN 30, respectively, the base station device 20-1 Transmits a multicast table transmission request to the PDSN 30 (S1). This multicast table transmission request includes one or more mobile station apparatus identification information for identifying one or more mobile station apparatuses 10 communicating with the base station apparatus 20-1. The PDSN 30 that has received this multicast table transmission request is a part of the stored multicast table, that is, the mobile station related to the multicast group to which the mobile station device 10 indicated by the mobile station device identification information included in the multicast table transmission request belongs. The device group information is transmitted to the base station device 20-1 (S2). The base station apparatus 20-1 receives the mobile station apparatus group information transmitted in this way, and configures and stores a multicast table.

  In the figure, the mobile station device 10-1 is located in the base station device 20-1, and the state in which streaming data is received from the PDSN 30 via the base station device 20-1 is described as an initial state (S3). , S4). In this initial state, during the communication with the base station apparatus 20-1, the mobile station apparatus 10-1 periodically receives a notification signal from a neighboring base station apparatus and acquires the reception level thereof. To -1 (S5). Based on the report from the mobile station device 10-1, the base station device 20-1 decides to hand over the mobile station device 10-1 to the base station device 20-2, and sends a handover request to the PDSN 30 (S6). The handover instruction is transmitted to the mobile station apparatus 10-1 (S7).

  The PDSN 30 that has received the handover request transfers the handover request to the base station apparatus 20-2 (S10), and continuously transmits streaming data to the base station apparatus 20-1 (S8). -1 transmits the streaming data from the PDSN 30 to the mobile station apparatus 10-1 (S9). Note that the streaming data transmitted from the PDSN 30 in S8 has a deletion request from the deletion request unit 41 via the transmission unit 33 after a predetermined time has elapsed in the time measurement by the predetermined time counting unit 39 of the PDSN 30 (S71 in FIG. 6). In addition, the base station device 20-1 receives the deletion request until the reception unit 21 of the base station device 20-1 receives the deletion request.

  The mobile station apparatus 10-1 that has received the handover instruction requests channel assignment to the base station apparatus 20-2, and establishes a communication path with the base station apparatus 20-2 (S11).

  The base station apparatus 20-2 acquires the multicast table from the PDSN 30 triggered by the reception of the handover request or the channel allocation request from the mobile station apparatus 10-1 whichever is earlier, and the same based on the multicast table. The mobile station device 10 (referred to as the mobile station device 10-2) in the multicast group is searched, and mobile station device identification information indicating the mobile station device 10-2 is acquired (S12).

  When the base station apparatus 20-2 acquires the mobile station apparatus identification information in S12, the mobile station apparatus 10-2 sequentially replicates the streaming data transmitted to the mobile station apparatus 10-2, and the base station replicated streaming data is used as the mobile station apparatus. 10-1 is sequentially transmitted (S13).

  When the mobile station apparatus 10-1 receives the base station replicated streaming data in S14, the mobile station apparatus 10-1 opens the communication path with the base station apparatus 20-1 (S15). In this case, the PDSN 30 performs the streaming data addressed to the mobile station device 10-1 via the base station 20-1 until the predetermined time has elapsed based on the time measurement by the predetermined time counting unit 39 (S71 in FIG. 6). Is continuously transmitted (S16, S16A). In addition, when the predetermined time has elapsed, the base station device 20-1 releases a communication path with the PDSN 30 (not shown). In this case, transmission of data addressed to the mobile station device 10-1 from the PDSN 30 to the base station 20-1 is completed. In addition, when transmitting the streaming data in S16 within the predetermined time, the PDSN 30 establishes a communication path with the base station device 20-2 (S17), and then transmits to the mobile station device 10-1. The transmission destination of the streaming data to be transmitted is set to the base station device 20-1 and the base station device 20-2. Then, the streaming data transmitted to the mobile station device 10-1 is received by the base station device 20-2 (S18) and also received by the base station device 20-1 (S16). ). In such a processing state, the base station apparatus 20-2 finishes the duplicate transmission (S19), and the streaming data received from the PDSN 30 is transmitted to the mobile station apparatus 10- via the base station apparatus 20-2. The process of transmitting to 1 is started (S20). Thereafter, the streaming data sequentially transmitted by the PDSN 30 is transmitted to the mobile station device 10-1 via the base station device 20-2 (S21, S22). Together with this, the streaming data sequentially transmitted by the PDSN 30 is transmitted to the mobile station apparatus 20-1 even when the mobile station apparatus 10-1 is handed over from the base station apparatus 20-1 to the base station apparatus 20-2. Streaming data is transmitted (S16).

  Next, processing after a handover request from the base station apparatus 20-1 to the PDSN 30 will be described in more detail based on FIG.

Based on the report from the mobile station device 10-1, the base station device 20-1 decides to hand over the mobile station device 10-1 to the base station device 20-2, and makes a handover request to the PDSN 30 (S6). In this case, the PDSN 30 receives the request at the receiving unit 34 and outputs the request to the predetermined time counting unit 39. The predetermined time counting unit 39 starts counting based on the request (S71). Then, the PDSN 30 performs the handover again to the handover source base station apparatus 20-1 before the predetermined time elapses before the predetermined time elapses in the time measurement by the predetermined time counting unit 39. Is determined by a first determination unit (not shown) (S72), and when the handover is performed again, the process of step S28 in FIG. 5 is performed to perform the handover source base station apparatus 20 Streaming data is continuously transmitted from -1 to the handover mobile terminal 10-1. On the other hand, if the handover is not executed again, a second determination unit (not shown) determines whether or not the predetermined time has elapsed (S73), and if the predetermined time has elapsed, the handover is performed. The original base station apparatus 20-1 is requested to delete at least the identification information of the handover mobile station apparatus 10-1 in the multicast table (S74).

  The present invention is not limited to the above embodiment. For example, although the streaming data has been described in the above-described embodiment, the above effect can be obtained by applying the present invention to data (real-time data) that is not limited to streaming data but requires real-time characteristics and retransmission control is limited. be able to.

  Further, in the above embodiment, the handover process has been described taking the handover process led by the base station apparatus 20 as an example, but the present invention can also be applied to other handover processes such as the mobile station apparatus 10 initiative.

It is a figure which shows the system configuration | structure of the mobile communication system which concerns on embodiment of this invention. It is a figure which shows the functional block of the mobile communication system which concerns on embodiment of this invention. It is a figure which shows the multicast table which concerns on embodiment of this invention. It is a figure which shows the mobile station apparatus-base station apparatus corresponding table which concerns on embodiment of this invention. It is a figure which shows the multicast table acquisition process which concerns on embodiment of this invention. It is a sequence diagram which shows the process based on the time measuring process which measures predetermined time in PDSN based on embodiment of this invention.

Explanation of symbols

1: mobile communication system, 10: mobile station device, 11, 21, 23, 31, 34: reception unit, 12: reception level acquisition unit, 13, 22, 24, 33, 35: transmission unit, 14, 27, 38: Handover execution unit, 20: Base station device, 25, 36: Multicast table storage unit, 26: Same data transmission determination unit, 28: Multicast table transmission request unit, 30: PDSN, 32: Destination determination unit, 37: Multicast Table transmission unit, 39: predetermined time counting unit, 40: network, 41: deletion request unit, 221: replication unit, 281: mobile station apparatus identification information acquisition unit.

Claims (4)

In a mobile communication system including a base station device and an exchange connected to the base station device, a data transmission method for transmitting data from the exchange to the mobile station device via the base station device,
An acquisition step of acquiring mobile station apparatus information indicating the mobile station apparatus on the base station apparatus side;
A data transmission step of transmitting the data from the exchange to the mobile station device via the base station device based on the acquired mobile station device information, and a mobile station device corresponding to the mobile station device information When performing handover from the base station apparatus to another base station apparatus, the base station apparatus side retains the acquired mobile station apparatus information for a predetermined period of time, and holds this until the predetermined period of time elapses. The data is transmitted from the exchange via the base station device based on the mobile station device information.
A data transmission method characterized by the above. The data transmission method according to claim 1,
When the mobile station apparatus corresponding to the mobile station apparatus information is handed over from the other base station apparatus to the base station apparatus while holding the mobile station apparatus information on the base station apparatus side, To continue transmission of the data from the exchange through the base station device,
A data transmission method characterized by the above. The data transmission method according to claim 1 or 2,
The data is streaming data.
A data transmission method characterized by the above. An exchange connected to a base station device and transmitting data to a mobile station device via the base station device,
Acquisition means for acquiring mobile station apparatus information indicating the mobile station apparatus;
Data transmission means for transmitting the data to the mobile station device via the base station device based on the acquired mobile station device information;
When the mobile station apparatus corresponding to the mobile station apparatus information is handed over from the base station apparatus to another base station apparatus, the mobile station apparatus comprises a time measuring means for measuring a predetermined time,
In the time measurement by the time measuring means, the data is transmitted to the base station device based on the acquired mobile station device information until the predetermined time elapses.
An exchange characterized by that.

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